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Pinpoint Test I: One Or More Stoplamps Are Inoperative




Stoplamps

Pinpoint Tests

Pinpoint Test I: One Or More Stoplamps Are Inoperative

Refer to Wiring Diagram Set 90, Turn Signal/Stop/Hazard Lamps for schematic and connector information. Diagrams By Number

Normal Operation

When the brake pedal is applied, the stoplamp switch routes voltage to the Smart Junction Box (SJB). The voltage is then routed through the SJB to the high mounted stoplamp.

For Explorer and Explorer Sport Trac, the SJB provides voltage on independent output circuits to the LH and RH stoplamps.

For Mountaineer, the SJB provides voltage to both rear stoplamps on a single output circuit.





This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- High mounted stoplamp
- LED module
- SJB



PINPOINT TEST I: ONE OR MORE STOPLAMPS ARE INOPERATIVE

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.

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I1 CHECK THE RECORDED DTCs FROM THE SJB SELF-TEST


- Check the recorded results from the SJB self-test.
- Is DTC C1788, B2048 or B2050 recorded?

Yes
For DTC C1788, GO to I2.

For DTC B2048 or DTC B2050, GO to I5.

No
GO to I7.

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I2 CHECK THE LH LED MODULE FOR A SHORT TO GROUND


- Disconnect: LH Rear Lamp C419.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB Self-Test.
- Clear the DTCs and repeat the SJB on-demand self-test.
- Is DTC C1788 still present?

Yes
GO to I3.

No
INSTALL a new LED module. RUN the on-demand self-test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation.

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I3 CHECK THE RH LED MODULE FOR A SHORT TO GROUND


- Disconnect: RH Rear Lamp C418.
- Enter the following diagnostic mode on the scan tool: SJB Self-Test.
- Clear the DTCs and repeat the SJB on-demand self-test.
- Is DTC C1788 still present?

Yes
GO to I4.

No
INSTALL a new LED module. RUN the on-demand self-test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation.

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I4 CHECK THE SJB STOPLAMP OUTPUT CIRCUIT FOR A SHORT TO GROUND (MOUNTAINEER)


- Ignition OFF.
- Disconnect: SJB C2280a.
- Measure the resistance between the LH rear lamp C419-1, circuit CLS44 (VT/BN), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to I15.

No
VERIFY the SJB fuse 27 (15A) is OK. If OK, REPAIR circuit CLS44 (VT/BN) for a short to ground. RUN the on-demand self-test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number

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I5 CHECK THE BULB HOLDER FOR A SHORT TO GROUND


- Disconnect: Inoperative Stoplamp.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB Self-Test.
- Clear the DTCs and repeat the SJB on-demand self-test.
- Is DTC B2048 or DTC B2050 still present?

Yes
GO to I6.

No
INSTALL a new bulb holder in question. TEST the system for normal operation.

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I6 CHECK THE SJB STOPLAMP OUTPUT CIRCUIT FOR A SHORT TO GROUND (EXPLORER/EXPLORER SPORT TRAC)


- Ignition OFF.
- Disconnect: SJB C2280a.
- For Explorer, measure the resistance between the inoperative rear lamp, harness side and ground as follows:









- For Explorer Sport Trac, measure the resistance between the inoperative rear lamp, harness side and ground as follows:









- Is the resistance greater than 10,000 ohms?

Yes
GO to I15.

No
VERIFY the SJB fuse 22 (15A) is OK. If OK, REPAIR the circuit in question for a short to ground. RUN the on-demand self-test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number

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I7 DETERMINE THE INOPERATIVE STOPLAMP


- Ignition OFF.
- Apply the brake pedal.
- Verify the high mounted stoplamp operation.
- Is the high mounted stoplamp illuminated?

Yes
If one rear stoplamp is inoperative, GO to I11.

For Mountaineer, if both rear stoplamps are inoperative, GO to I13.

For Explorer Sport Trac, if both rear stoplamps are inoperative, GO to I14.

For Explorer, if both rear stoplamps are inoperative, GO to I15.

No
GO to I8.

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I8 CHECK FOR VOLTAGE TO THE HIGH MOUNTED STOPLAMP


- For Explorer or Mountaineer, while applying the brake pedal, measure the voltage between the high mounted stoplamp C475-1, circuit CCB08 (VT/WH), harness side and ground.




- For Explorer Sport Trac, while applying the brake pedal, measure the voltage between the high mounted stoplamp C927-3, circuit CCB08 (VT/WH), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to I9.

No
GO to I10.

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I9 CHECK THE HIGH MOUNTED STOPLAMP GROUND CIRCUIT FOR AN OPEN


- Disconnect: High Mounted Stoplamp C475 (Explorer, Mountaineer) or C927 (Explorer Sport Trac).
- For Explorer or Mountaineer, measure the voltage between the high mounted stoplamp C475-1, circuit CCB08 (VT/WH), harness side and the high mounted stoplamp C475-2, circuit GD149 (BK/GY), harness side.




- For Explorer Sport Trac, measure the voltage between the high mounted stoplamp C927-3, circuit CCB08 (VT/WH), harness side and the high mounted stoplamp C927-1, circuit GD133 (BK), harness side.




- Is the voltage greater than 10 volts?

Yes
INSTALL a new high mounted stoplamp. TEST the system for normal operation.

No
REPAIR circuit GD149 (BK/GY) or circuit GD133 (BK) for an open. TEST the system for normal operation.

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I10 CHECK THE HIGH MOUNTED STOPLAMP VOLTAGE SUPPLY CIRCUIT FOR AN OPEN


- Disconnect: SJB C2280a.
- For Explorer or Mountaineer, measure the resistance between the high mounted stoplamp C475-1, circuit CCB08 (VT/WH), harness side and the SJB C2280a-15, circuit CCB08 (VT/WH), harness side.




- For Explorer Sport Trac, measure the resistance between the high mounted stoplamp C927-3, circuit CCB08 (VT/WH), harness side and the SJB C2280a-15, circuit CCB08 (VT/WH), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to I15.

No
REPAIR circuit CCB08 (VT/WH) for an open. TEST the system for normal operation.

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I11 CHECK THE REAR LAMP GROUND CIRCUIT FOR AN OPEN


- Place the headlamp switch in the PARKING LAMPS ON position.
- Does the rear lamp in question illuminate?

Yes
For Mountaineer, TURN the parking lamps off. GO to I12.

For Explorer or Explorer Sport Trac, TURN the parking lamps off. GO to I13.

No
REPAIR the ground circuit in question for an open. CLEAR the DTCs. REPEAT the self-test.

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I12 CHECK FOR VOLTAGE TO THE REAR STOPLAMP


- Disconnect: Inoperative Rear Lamp.
- While applying the brake pedal, measure the voltage between the LH rear lamp (LED module) C419-1, circuit CLS44 (BU/RD), harness side and ground; or between the RH rear lamp (LED module) C418-1, circuit CLS44 (BU/RD), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
INSTALL a new LED module. TEST the system for normal operation.

No
REPAIR circuit CLS44 (BU/RD) for an open. TEST the system for normal operation.

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I13 CHECK THE REAR STOPLAMP VOLTAGE SUPPLY CIRCUIT FOR AN OPEN


- Disconnect: Inoperative Rear Lamp.
- Disconnect: SJB C2280a.
- Measure the resistance between the inoperative rear lamp, harness side and the SJB, harness side as follows:









- Is the resistance less than 5 ohms?

Yes
GO to I15.

No
REPAIR the circuit in question for an open. CLEAR the DTCs. REPEAT the self-test.

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I14 CHECK THE SHARED REAR STOPLAMP GROUND CIRCUIT FOR AN OPEN


- Place the headlamp switch in the PARKING LAMPS ON position.
- Are both rear parking lamps inoperative?

Yes
REPAIR circuit GD149 (BK/YE) for an open. CLEAR the DTCs. REPEAT the self-test.

No
GO to I15.

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I15 CHECK FOR CORRECT SJB OPERATION


- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new SJB. REFER to Body Control Systems. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.

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